﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.ComponentModel;
using System.Globalization;

namespace System.Windows.Forms;

/// <summary>
///  OpacityConverter is a class that can be used to convert opacity values from one
///  data type to another. Access this class through the TypeDescriptor.
/// </summary>
public class OpacityConverter : TypeConverter
{
    /// <summary>
    ///  Determines if this converter can convert an object in the given source
    ///  type to the native type of the converter.
    /// </summary>
    public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
    {
        if (sourceType == typeof(string))
        {
            return true;
        }

        return base.CanConvertFrom(context, sourceType);
    }

    /// <summary>
    ///  Converts the given object to the converter's native type.
    /// </summary>
    public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
    {
        if (value is string valueString)
        {
            string text = valueString.Replace('%', ' ').Trim();
            double val = double.Parse(text, CultureInfo.CurrentCulture);
            int indexOfPercent = valueString.IndexOf('%');
            if (indexOfPercent > 0 && (val >= 0.0 && val <= 1.0))
            {
                val /= 100.0;
                text = val.ToString(CultureInfo.CurrentCulture);
            }

            double percent;
            try
            {
                if (!Control.UseComponentModelRegisteredTypes)
                {
                    percent = (double)TypeDescriptor.GetConverter(typeof(double)).ConvertFrom(context, culture, text)!;
                }
                else
                {
                    // Call the trim safe API
                    percent = (double)TypeDescriptor.GetConverterFromRegisteredType(typeof(double)).ConvertFrom(context, culture, text)!;
                }

                // Assume they meant a percentage if it is > 1.0, else they actually
                // typed the correct double.
                if (percent > 1.0)
                {
                    percent /= 100.0;
                }
            }
            catch (FormatException e)
            {
                throw new FormatException(
                    string.Format(SR.InvalidBoundArgument,
                        "Opacity",
                        text,
                        "0%",
                        "100%"), e);
            }

            // Now check to see if it is within our bounds.
            if (percent is < 0.0 or > 1.0)
            {
                throw new FormatException(
                    string.Format(SR.InvalidBoundArgument,
                        "Opacity",
                        text,
                        "0%",
                        "100%"));
            }

            return percent;
        }

        return base.ConvertFrom(context, culture, value);
    }

    /// <summary>
    ///  Converts the given object to another type. The most common types to convert
    ///  are to and from a string object. The default implementation will make a call
    ///  to ToString on the object if the object is valid and if the destination
    ///  type is string. If this cannot convert to the destination type, this will
    ///  throw a NotSupportedException.
    /// </summary>
    public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
    {
        if (value is double val && destinationType == typeof(string))
        {
            int perc = (int)(val * 100.0);
            return $"{perc}%";
        }

        return base.ConvertTo(context, culture, value, destinationType);
    }
}
